I have a server application implemented using Dropwizard and Gradle as Build System. Now I want to integrate Apache Mahout for some recommender system action.
After adding the Mahout dependency and try to run, I get exceptions.
My initial dependencies look like
dependencies {
compile 'io.dropwizard:dropwizard-core:0.9.1'
compile 'io.dropwizard:dropwizard-jdbi:0.9.1'
compile 'mysql:mysql-connector-java:5.1.37'
compile 'redis.clients:jedis:2.8.0'
compile 'com.google.guava:guava:18.0'
compile 'joda-time:joda-time:2.9.1'
compile 'org.apache.commons:commons-math3:3.4.1'
}
For doing some basic recommender system stuff I integrate the dependency
compile 'org.apache.mahout:mahout-mr:0.11.1'
When I now run the application I get a NoClassDefFoundException:
WARN [2015-12-07 15:03:09,696] org.glassfish.jersey.internal.Errors:
The following warnings have been detected: WARNING: HK2 service reification
failed for [com.sun.jersey.core.impl.provider.entity.MimeMultipartProvider]
with an exception:
MultiException stack 1 of 2
java.lang.NoClassDefFoundError: javax/mail/internet/ParseException
So I tried to integrate this stuff as extra dependency via
compile 'com.sun.mail:javax.mail:1.5.4'
Running again the application, I get a different exception:
WARN [2015-12-07 15:05:02,161] org.glassfish.jersey.internal.Errors: The
following warnings have been detected: WARNING: Unknown HK2 failure detected:
MultiException stack 1 of 2
java.lang.NullPointerException at
com.sun.jersey.core.provider.jaxb.AbstractJAXBProvider.setConfiguration(AbstractJAXBProvider.java:109)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
The Code that causes the exception comes from Jersey:
@Context
public void setConfiguration(FeaturesAndProperties fp) {
formattedOutput = fp.getFeature(FeaturesAndProperties.FEATURE_FORMATTED); // << Crash here
xmlRootElementProcessing = fp.getFeature(FeaturesAndProperties.FEATURE_XMLROOTELEMENT_PROCESSING);
}
So it seems like the feature is null here and we can't do anything with it. Anyone an idea what's going on, or how I can manage this?
The problem was / is that Dropwizard ships with a Jersey dependency (in my case org.glassfish.jersey in 2.22.x), and Apache Mahout ships with a different Jersey dependency (in my case com.sun.jersey in 1.9).
So excluding the Mahout Jersey dependency does the job. In my case this is done by
compile('org.apache.mahout:mahout-integration:0.11.1') {
exclude group: 'com.sun.jersey'
}